The present invention relates to a light measuring device for use, for example, in photography for measuring the intensity of light reflected from or incident on an object to be photographed and for indicating one or more values of the exposure parameters, such as an aperture value, exposure value or shutter speed, as a function of the measured light intensity. More particularly, the present invention relates to an improvement in a display system employed in a light meter.
Conventionally, there has been proposed a light meter having a plurality of indication dots, composed of either light emitting diodes or as provided by a liquid crystal display, aligned such that the position of each dot relative to the other represents a specific value, such as, for example, an exposure parameter, as a function of the measured light intensity. An example of these dot display type arrangements, is disclosed in U.S. Pat. No. 3,895,875 to Kitaura et al., which issued on July 22, 1975. According to this arrangement, it is possible to energize two or more light emitting diodes at the same time on the basis of the measuring operations carried out for different objects. Although this dot display system is advantageous in that it visually indicates the difference between the values represented by the displayed dots, e.g., the obtained aperture values which are suitable for different objects, it requires a large space to accommodate the indication dots in order to acquire a fairly good identification or determination of the value indicated by each dot. Furthermore, since the dot merely shows the represented value by means of its relative position with respect to the other dots, the display element, i.e., the dot, by itself cannot indicate an absolute or exact value.
Another type of conventional light meter is a numeral display type which includes one or more, e.g. three, frames of segment indicators, each frame being so actuated as to form a figure of a numeral from 0 to 9. This type of arrangement is disclosed in U.S. Pat. No. 4,176,955 to Yamada et al., which issued on Dec. 4, 1979. According to this arrangement, since a set of three-frame-segment indicators occupies a large space in the light meter, it is difficult to employ two or more sets of such segment indicators in order to display two or more values at a time. Even if two or more sets of segment indicators were provided, it is difficult to visually compare the difference between the displayed values. Although the arrangement disclosed in U.S. Pat. No. 4,176,955 includes a display system having both dot indicators and segment indicators, the segment indicators merely show a calculated result obtained from stored values. There is no means to display any of th stored light intensity values in detail through the segment indicators.
A similar apparatus is disclosed in U.S. Pat. No. 4,309,090 to Yamada et al, which issued on Jan. 5, 1982 and assigned to the same assignee as the present application. This patent teaches the use of dot indicators and segment indicators at the same time with dot indicators showing the exposure parameter based on center-weighted measurement and segment indicators showing the exposure parameter based on average measurement, or vice versa depending on selection by a selecting switch. This application also has no means to display any of the stored light intensity values in detail through the segment indicators.